Many different types of air-flow deflectors have been proposed for use with tractor-trailer rigs in order to reduce the effects of wind resistance. Typical of such deflectors are the ones shown by Meadows (U.S. Pat. No. 3,695,673) and Geiger (U.S. Pat. No. 3,947,065).
Air-flow deflectors have been combined with air grilles for greater control of the air-flow as shown in the two Engel patents (U.S. Pat. No. 4,840,422 and U.S. Pat. No. 4,957,325). The patent to Landry (U.S. Pat. No. 4,103,957) shows another attempt to develop more of an air management approach, this time by the use of an airfoil which directs some of the air-flow upward and uses part of the air-flow to create a vortex between the airfoil and the trailer.